In conventional, in order to speed up a data transfer between communication processing systems, there is a data transfer system structured such as to store an update data of a data file data in an update data file by a sending side communication processing system, and transfer a difference information between the data of the data file and the update data of the update data file at the time of transferring the data to a receiving side communication processing system (for example, refer to Japanese Patent Laid-Open Publication No. 10-289172).
Further, as a technique for managing the update data, there has been developed a technique called as a snap shot structured such that in the case that the update is executed with respect to a storage volume after a certain time point in the storage system, the data before the update is stored in the other storage volume and the data at a certain time point can be referred with respect to the storage volume.